Implantable medical devices are used to monitor and treat a variety of conditions. Examples of implantable medical devices are implantable loop recorders, implantable pacemakers and implantable cardioverter-defibrillators (ICDs), which are electronic medical devices that monitor the electrical activity of the heart and/or provide electrical stimulation to one or more of the heart chambers, when necessary. For example, cardiac signals may be monitored by an implantable device to detect an arrhythmia, i.e., a disturbance in heart rhythm, with appropriate electrical stimulation pulses being provided, at a controlled rate, to selected chambers of the heart in order to correct the arrhythmia and restore the proper heart rhythm.
The implantable medical devices are preferably designed with shapes that are easily tolerated in the patient's body while minimizing patient discomfort. As a result, the corners and edges of the devices are typically designed with generous radii to present a package having smoothly contoured surfaces. It is also desirable to minimize the volume occupied by the devices as well as their mass to further limit patient discomfort. As a result, the devices continue to become thinner, smaller, and lighter.
In order to perform their monitoring, pacing and/or cardioverting-defibrillating functions, the devices must have an energy source, e.g., at least one battery. The batteries employ packaging techniques that enclose the internal components in a casing which is further enclosed in a housing of the implantable medical device. While these battery packages have proven effective for housing and electrically insulating the battery components, there are various inefficiencies associated with the batteries.
One challenge is the excess volumetric size of the implantable medical device caused by placing these batteries within the contoured implantable medical device. As stated above, implantable medical devices are preferably designed with corners and edges having generous radii to present a package having smoothly contoured surfaces. When the battery is placed within the contoured implantable device, the contours of these devices do not necessarily correspond and thus the volume occupied within the implantable device cannot be optimally minimized to further effectuate patient comfort.
Another challenge associated with the conventional battery construction pertains to the electrical connections from the batteries to various components of the implantable device. In a typical implantable device battery, the battery enclosures are formed from metallic or other conductive material. Thus, interconnection inefficiency arises due to the manufacturing limitations and material properties of the battery that impact the device performance.
In accordance with techniques of conventional battery construction such as that disclosed in U.S. Pat. No. 7,442,465, a passive connection of one of the anode or cathode (battery electrodes) is made to the case so that the battery case itself functions as a negative or positive terminal. Such conventional construction requiring that the battery case be connected to one of the two battery terminals in the device poses a challenge to the miniaturization of the implantable medical devices.
For the foregoing reasons, there is a need for an improved implantable medical device assembly with efficient utilization of the device housing.